50D + 400mm F5.6 +1.4

At present I have a 30D and the 400mm F5.6 and the 1.4x multiplier and am considering upgrading to the 50D. The above combination does not autofocus (without covering pins) but I have heard that the 50D might. Has anyone tried to autofocus that lens combination with a 50D? In particular how good is it at autofocusing a sequence of shots of a bird in flight using that lens combination in good and poor light conditions?